论文部分内容阅读
Cr12冷冲栽模崩脆失效的普遍原因是碳化物的形态和分布不合理,四步热处理使碳化物“小、散、匀、圆、钝”,取得较理想的形态和分布,模具寿命达到42—55万次,比常规工艺的模具寿命提高两倍。本文用吉布斯(Gibbs)汤姆生(Thompson)公式,从热力学的角度阐述四步处理使条块状碳化物棱角趋圆趋钝是必然趋势,从组织遗传性的观点出发,指出四步法中的第二步——高温回火,使结晶有序的粗晶马氏体组织得到强烈分解,从而阻止了第一步1100℃过热淬火的粗晶缺陷“遗传”给下一代——第三步980℃淬火;第一步及第二步处理之后,碳化物小、散、匀,圆、多,由于相界作用及点阵畸变的热力学原因,经第三步——980℃淬火及第四步——低温回火后,得到的马氏体晶粒不是“粗了”,而是极细。“小、散、匀、圆、钝”的碳化物形态和分布,加上理想的细晶强化,正是四步热处理使Cr12冷冲栽模强韧化的根本原因。
The common reason for the collapse failure of Cr12 cold-formed die is that the shape and distribution of carbides are unreasonable. The four-step heat treatment makes the carbides small, scattered, uniform, round and dull, and achieves the ideal shape and distribution. The die life reaches 42-55 million times, than the conventional mold life increased by twice. In this paper, Gibbs Thompson formula is used to describe the four-step process from the thermodynamic point of view so that the angular carbide bar-like obtuse is an inevitable trend, from the organization point of view of genetic point out four-step method In the second step - high-temperature tempering, so that crystalline ordered martensite coarse grained to be strongly decomposed, thus preventing the first step 1100 ℃ overheat quenching coarse grain defects “to” the next generation - the third Step 980 ℃ quenching; the first step and the second step after treatment, carbide small, scattered, uniform, round, and more, due to the phase boundary effect and the lattice distortion of the thermodynamic reasons, the third step - 980 ℃ quenching and Four-Step - After tempering at low temperature, the resulting martensite grains are not “coarse” but very fine. “Small, scattered, uniform, round, blunt” carbide morphology and distribution, coupled with the ideal fine grain strengthening, it is the four-step heat treatment to make Cr12 cold punching plant the root causes of toughening and toughening.